Last week, OnEarth.org editor Scott Dodd sat down in New York City’s Bryant Park to talk water with Alex Prud’homme, author of The Ripple Effect: The Fate of Fresh Water in the 21st Century , and documentary filmmaker Irena Salina, a producer of 2008’s Flow and an editor of this year’s Written in Water: A Message for the Future . Here are some notes. When it comes to the world’s water supply, Prud’homme and Salina agreed, we’ve got some serious issues. For one thing, the abundance of freshwater is likely to ebb as global temperatures climb, and a growing population may soon find that there just isn’t enough of the stuff. Also, while water pollution has long been cause for concern, the addition in the past few decades of pharmaceuticals and thousands of other new chemicals to the nation’s list of groundwater contaminants means there are ever-more-disturbing health and ecosy...